About Closing the Volume
Click > to give the system final instructions on how to gather the volume. Close enables you to specify how a volume should be capped or enclosed, as well as whether to close internal loops in the volume such as hole openings in bounding surfaces. When you define a mold volume, the menu for closure appears automatically after you indicate that you have completed defining the volume. Once you have specified the closure instructions, the Close command appears in the GATHER STEPS or VOL GATHER menu, enabling you to redefine or delete the closure instructions.